The facts
Matthew J. Holman of the Center for Astrophysics | Harvard & Smithsonian and collaborators identified the object using software that links moving detections across nights. NSF says the Minor Planet Center assigned its provisional designation. [1][2]
The study uses 30 Rubin detections on 20 nights between 4 March and 11 July 2026, plus older Dark Energy Camera images. The adopted orbit fit uses 74 observations spanning 2016–2026. [2]
The authors infer a diameter of 612–1,530 kilometres if geometric reflectivity lies between 25% and 4%. This is a model-dependent range, not a direct size measurement. [2]
Holman and 21 co-authors' preprint was first posted to arXiv on 28 October and is submitted to The Astronomical Journal. The checked manuscript is not presented as a peer-reviewed publication. [2]
Still unconfirmed
- The precise diameter, surface reflectivity and final dwarf-planet classification.
Sources
References support the numbered facts above. Source checks: 30 Oct 2026, 10:28 UTC.
- New dwarf planet candidate discovered by NSF–DOE Rubin Observatory
US National Science Foundation / Rubin Observatory · Primary source · 27 Oct 2026
Actual discovery release read. NSF identifies it as an edited Rubin release; NSF, the observatory and author institutions are not counted as independent reporting owners.
- 2026 ED138: A Large Trans-Neptunian Object in Early Rubin Observatory Data, and How Many More May Remain
Matthew J. Holman, Mario Jurić and collaborators / arXiv · Primary source · 28 Oct 2026
DOI 10.48550/arXiv.2610.38693, v1. Actual abstract and manuscript observational, validation and orbit-fitting sections read. The served PDF is a draft dated 30 October; arXiv records first posting 28 October. Study calculations were not independently reproduced. The size range assumes an albedo interval.
- Astronomers found a mysterious object beyond Neptune, and it could be a new dwarf planet
Space.com / Mike Wall · Reporting · 29 Oct 2026
Actual report read. Space.com/Future is separate from the government-funded discovery project. It corroborates the discovery announcement and preserves the provisional classification; it is not another team's independent observation campaign.